Probably being sidelined while manufacturers focuses on the most popular cartridges. The .257 Roberts sounds like a wonderful cartridge but it is probably being overwhelmed by the demand for the more frequently purchased ammo. Hornady quit making a bunch of their bullets so they could focus on the more popular ones. They have a two year backlog in bullets alone. Most ammo manufacturers are backlogged with existing orders for at least one year.
Also, the Roberts is probably much more of a hunting season round so maybe it will start to show up shortly, whereas rounds like the .308 are in high demand year round.
I've been thinking of a rifle in a sub-.30 cal chambering and the Roberts is one of the candidates. Seems like a nice cartridge that has plenty to get the job done and mild enough for everyone in the family.
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